Ian Cordasco 87a9c75ea3 Add Python API Reference documentation

This corrects some typos in earlier documentation patches, removes
outdated API reference documentation, and organizes all API reference
documentation under one chapter.

This also leaves room for future API versions and more specific API
reference documentation being broken out into sub-sections.

Change-Id: I5391a1acc7d1669207b3d10039a196d026216f40

2017-03-17 14:38:02 -05:00

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Using the Hosts API

Here we will assume that we already have a ~cratonclient.client.Client instance configured with the appropriate authentication method (as demonstrated in usage-auth).

Listing Hosts

The Hosts API implements pagination. This means that by default, it does not return all hosts known to Craton. To ignore page limits and offsets, we can allow cratonclient to do handle pagination for us:

for host in craton.hosts.list():
    print_host_info(host)

By default ~cratonclient.v1.hosts.HostManager.list will handle pagination for you. If, instead, you want to handle it yourself you will want to do something akin to:

first_page_of_hosts = list(craton.hosts.list(autopaginate=False))
marker_id = first_page_of_hosts[-1].id
second_page_of_hosts = list(craton.hosts.list(
    autopaginate=False,
    marker=marker_id,
))
marker_id = second_page_of_hosts[-1].id
third_page_of_hosts = list(craton.hosts.list(
    autopaginate=False,
    marker=marker_id,
))
# etc.

A more realistic example, however, might look like this:

hosts_list = None
marker = None
while hosts_list and hosts_list is not None:
    hosts_list = list(craton.hosts.list(
        marker=marker,
        autopaginate=False,
    ))
    # do something with hosts_list
    if hosts_list:
        marker = hosts_list[-1].id

This will have the effect of stopping the while loop when you eventually receive an empty list from craton.hosts.list(...).

Creating Hosts

Hosts live inside either a Region or Cell in Craton. To create a host, one needs:

A unique name
A unique IP address
A "device type" (this is freeform), e.g., "server", "container", "nova-vm", etc.
A cloud ID
A region ID

host = craton.hosts.create(
    name='my-host-0',
    ip_address='127.0.1.0',
    device_type='server',
    cloud_id=cloud_id,
    region_id=region_id,
    note='This is my host, there are many like it, but this is mine.',
    variables={
        'some-var': 'some-var-value',
    },
)

Retrieving a Specific Host

Hosts can be retrieved by id.

host = craton.hosts.get(1)

Using a Host's Variables

Once we have a host we can introspect its variables like so:

host = craton.hosts.get(host_id)
host_vars = host.variables.get()

To update them:

updated_vars = {
    'var-a': 'new-var-a',
    'var-b': 'new-var-b',
    'updated-var': 'updated value',
}
host.variables.update(**updated_vars)

To delete them:

host.variables.delete('var-a', 'var-b', 'updated-var')

Updating a Host

We can update a host's attributes (but not its variables) like so:

craton.hosts.update(
    host_id,
    name='new name',
    note='Updated note.',
)

Most attributes that you can specify on creation can also be specified for updating the host as well.

Deleting a Host

We can delete with only its id:

craton.hosts.delete(host_id)

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